Lecture 15

Question 1

First line of defense

Answer 1

Innate, nonspecific, includes physical (skin, mucus) and chemical barriers (low pH, digestive enzymes)

Question 2

Second line of defense

Answer 2

Innate and mostly non-specific, WBCs inflammation, fever, complement system, interferon

Question 3

Third line of defense

Answer 3

Specific and provides memory, T and B lymphocytes plus antibodies

Question 4

Primary defenses (physical)

Answer 4

Skin: keratin, tough and waterproof
Mucus: traps microbes, protects body openings without skin
Cilia: moves mucus/secretions
Urine: flushes out microbes
BBB
Sneezing and coughing
Defecation and vomiting
Normal microbiota

Question 5

Primary defenses (chemical)

Answer 5

Lysozyme in tears, saliva, sweat: enzyme hydrolyses peptidoglycan
Defensins in various cells and tissues: damage bacterial and fungal membranes
Sebum: inhibits growth
Sweat: high lactic acid and electrolytes
Hydrochloric acid in stomach
Acidic vagina

Question 6

Immunology

Answer 6

Study of all features of the body’s second and third lines of defense

Question 7

Immune system tasks

Answer 7

Surveillance of the body, recognition of self and foreign material, destruction of foreign entities

Question 8

Major histocompatibility complex (MHC)

Answer 8

Protein “self tags” found on the surface of all human cells except RBCs

Question 9

How MHCs are made

Answer 9

Exons are randomly selected from the MHC genes during development to form an individuals MHC, everyone’s MHC is different

Question 10

Circulatory system immune functions

Answer 10

Blood carries plasma with proteins and nutrients, plasma build up causes swelling, leukocytes in blood, platelets for clotting

Question 11

Lymphatic system immune functions

Answer 11

Provides route to return extracellular fluid to the circulatory system, drain off system for inflammatory response
Also surveillance, recognition, and protection through lymphocytes, phagocytes, and antibodies

Question 12

Lymph vessels

Answer 12

Run parallel along blood vessels transporting lymph and collecting ECF from tissue to return to blood circulation

Question 13

Lymph

Answer 13

Plasma like liquid that contains numerous WBCs especially lymphocytes, and infectious agents

Question 14

Lymph nodes

Answer 14

Small bean-shaped organs stationed along the body that filter lymph fluid and house lymphocytes

Question 15

Thymus

Answer 15

Gland above heart involved in T cell maturation

Question 16

Bone marrow

Answer 16

Site of blood cell production

Question 17

Lymphoid tissue

Answer 17

Patches of B and T cells found near portals of entry in the body

Question 18

MALT

Answer 18

Mucus associated lymphoid tissue
Around areas with a lot of mucus

Question 19

Lymph flow

Answer 19

Flows only towards the heart moved by skeletal muscle contractions of muscles surrounding lymph vessels

Question 20

Basophils

Answer 20

Defenders against local invasion of pathogens, live in the blood, releases histamine causing inflammatory response, granulocyte

Question 21

Mast cells

Answer 21

Mast cells line the tissue exposed to the environment, first line defenders against local invasions, release chemokines that stimulate movement of other WBCs to site of infection and histamine

Question 22

Histamine

Answer 22

Starts inflammatory response by causing vasodilation bringing more WBCs to area

Question 23

Neutrophils

Answer 23

Phagocytes first responders, most abundant WBC (60% +), engulf and kill bacteria

Question 24

Monocytes

Answer 24

Circulate in blood and become macrophages when activated

Question 25

Macrophage

Answer 25

Largest WBC, super active phagocytes, come in last and process foreign molecules plus present them to lymphocytes, overlaps with third line of defense

Question 26

Eosinophils

Answer 26

Specialized granulocytes, active against fungal and helminth infections, use cytokines to punch holes in worms

Question 27

Dendritic calls

Answer 27

Engulf pathogens and activate other immune cells by presenting foreign molecules to lymphocytes, taste testers Throughout tissue that is close to the external environment Long thin processes resemble dendrites Overlap with third line

Question 28

Lymphocytes

Answer 28

Third line of defense provide specific immune response and memory to foreign invaders Two types: B and T lymphocytes

Question 29

Diapedesis

Answer 29

Leukocytes leave the circulatory system and enter the extracellular space to check for self and non-self cells Can be increased with chemokines released by mast cells stimulating infiltration of WBCs via a chemical gradient Made possible by leaky capillaries and endothelial tissue of vessels

Question 30

Phagocytosis by neutrophils and macrophages

Answer 30

1. Chemotaxis and adherence of microbe to phagocyte 2. Ingestion of microbe by phagocyte 3. Formation of phagosome 4. Fusion of phagosome and lysosome to form phagolysosome 5. Digestion of ingested microbe by enzymes 6. Formation of residual body containing indigestible material 7. Discharge of waste material

Question 31

Inflammation

Answer 31

Secondary defense, response to infection or chemical/physical stimuli 4 signs redness, pain, swelling, heat

Question 32

Goal of inflammation

Answer 32

Either destroy and remove pathogen ory confine it to a specific area and stimulate tissue repair

Question 33

1st response of inflammation

Answer 33

Vasoconstriction, prevents blood loss until clot forms, bacteria in wound signals mast cells to sound the alarm by releasing chemokines and histamine

Question 34

Second response of inflammation

Answer 34

Histamine causes vasodilation increasing blood flow to infected area causing redness and heat given off by increased blood flow, increased vascular permeability causes leaking of fluids from blood vessels into tissue

Question 35

Third response of inflammation

Answer 35

Swelling from increased extracellular fluid in the tissue, pressure from swelling on nerve endings causes pain, site infiltrated by neutrophils that are attracted by chemokines phagocytize sometimes forming pus

Question 36

Fourth response of inflammation

Answer 36

Macrophages clean up debris, dead cells, leftover bacteria from infection Fluid is reabsorbed by lymph system Tissue either returns to normal state or scar tissue forms

Question 37

Fever

Answer 37

Secondary defense, elevated body temperature, starts when pathogens release pyrogens that bind the hypothalamus and reset it to a higher temperature Macrophages and other immune cells can cause never by secreting the cytokine interleukin-1, a pyrogen

Question 38

Response to fever

Answer 38

Body tries to maintain the set temperature via changes in vasculature, metabolism, and musculature Like shivering

Question 39

Benefits of fever

Answer 39

Inhibits multiplication of temperature sensitive microbes, increases metabolism and stimulates immune reactions,

Question 40

Dangers of fever

Answer 40

If temperatures get too high can damage human proteins, high or prolonged fevers especially in children need fever-suppressant drugs

Question 41

Interferon (IFN)

Answer 41

Small protein produced by virally infected cells, bind to nearby cells and induce expression of antiviral proteins to protect nearby cells from the virus

Question 42

Complement

Answer 42

Second line of defense 30 serum proteins that work in a cascade to destroy pathogens, proteins activated by cleavage, complement or assist in immune responses

Question 43

Complement system

Answer 43

Complement proteins activated by self-cleavage, surround pathogen making them more appealing to macrophages, a process called opsonization, complements also form membrane attack complexes that punch holes in bacterial all membranes causing lysis, bind to mast cells signaling them to release chemokines and histamine triggering inflammatory response

Question 44

Classical pathway

Answer 44

Antibody binding to pathogen activates complements that can lead to all 3 complement functions: opsonization, cytolysis via macrophages, and inflammation

Question 45

Alternative pathway

Answer 45

Complement proteins bind directly to surface proteins on bacteria causing self cleavage leading to opsonization, inflammation, and cytolysis Pathway doesn't work if pathogen has capsule

Question 46

Lectin pathway

Answer 46

Lectin binding to lectin receptors on pathogens activating complements leading to opsonization, inflammatory, and cytolysis

Question 47

Third line of defense

Answer 47

Lymphocytes, B cells that mature in bone marrow, humoral immunity because found in blood and lymphatics protect bodily fluids

Question 48

T cells

Answer 48

Mature in the thymus, engage in cell-mediated immunity, intracellular threats like viruses, pathogen has to be presented to them